Improvements in electrical connectors for ceiling and wall fittings



Jan. 17, 1961V o. MASON 2,968,784 IMPROVEMENTS IN ELECTRICAL CONNECTORS Y FOR CEILING AND WALL FITTINGS Filed Dec. l0, 1956 3 Sheets-Sheet 1 Inventor` OSCAR MASON Attorney! Jan, 17, 1961 o. MASON 2,968,784

- IMPROVEMENTS IN ELECTRICAL coN ToRs FOR CEILING AND WALL FITTI Filed Deo. 10, 1956 5 Sheets-*Sheet 2 ,il FIGS.

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l lll 3 lnventor` L Attornev Jan. 17, 1961 o. MASON 2,968,784 IMPROVEMENTS TN ELECTRICAL CONNECTORS FOR CEILING AND WALL FITTINGS Filed Deo. l0, 1956 3 Sheets-Sheet 5 FIGJO.

Inventor OSCAR MASON United States Patent O IMPROVEMENTS IN ELECTRICAL CONNECTORS FOR CEILING AND WALL FITTINGS Oscar Mason, Cliltords Inn, Fleet St., London, England Filed Dec. 10, 1956, Ser. No. 627,359 Claims priority, application Great Britain Dec. 22, 1955 3 Claims. (Cl. 339-197) 'Ihis invention relates to electrical connectors and more particularly to ceiling and wall fittings, for example ceiling roses, for electric light and power circuits.

It is an object of the present invention to provide an improved electrical connector, more particularly an improved ceiling rose or other ceiling attachment, comprising two contact-supporting parts, one of which is adapted to be tixed to the ceiling or other support, while the other is adapted to be detachably connected to the xed part.

According to the present invention there is provided an electrical connector comprising two contact-supporting parts one of which is adapted to be detachably connected to the other part, an undercut transverse groove being formed in one of said parts into which groove the other part is adapted -to slide to bring the contacts in the two parts into register, and means for automatically locking the said parts in position when the contacts therein are in register.

Further according to the invention there is provided an electrical connector, more particularly but not exclusively for ceiling-supported electric light iittings, comprising a fixed part having an undercut groove in one surface thereof, a detachable part adapted to slide into said groove and electrical contact members in each of said parts, characterised by the fact that the contact members in one of said parts are spring-loaded and have convex ends while u the contact members in the other part have concave contact surfaces, so that the two parts of the connector are automatically locked in position by the contact members when the said members are in register. l

Further according to the invention there is provided an electrical connector as set forth above, in which the contact members in the detachable part are springfloaded and have projecting convex ends, while the contact members in the fixed part have concave ends with which the said convex ends cooperate, so that the two parts are automatically locked in position when the said members are in register.

Further according to the invention there is provided an electrical connector as set forth above in which the contact members in the detachable part are spring-loaded and have projecting convex ends, while the co'ntact members in the xed part have concave ends with which the said convex ends cooperate, and in which the said concave ends are disposed in recesses in the iixed part whereby risk of accidental contact with the contact members in the xed part when the detachable part is removed is avoided or reduced.

Alternatively the contact members in the upper part may be spring-loaded and have projecting convex lower ends, while the contact members in the lower part have concave contact surfaces so that the two parts of the connector are electrically locked in position by the contact members when said members are in register.

'Ihe invention is illustrated by way of example in the accompanying drawings in which:

Figure 1 is a side view of a ceiling rose according to the invention showing the fixed part and the detachable part removed therefrom;

Figure 2 is a side view corresponding with Figure l showing the two parts in connected position;

Figure 3 is a part sectional elevation corresponding with Figure 2;

Figure 4 is a plan view from underneath of the upper fixed part;

Figure 5 is a side view taken at right angles to Figure 2.

Figure 6 is a plan view of the lower detachable part;

Figure 7 is a part sectional elevation of a modilied construction;

Figure 8 is a plan view of the upper tixed part of the construction of Figure 7;

Figure 9 is a plan view of the lower detachable part of the construction of Figure 7', and

Figure 10 is a sectional side elevation of a further modification.

Referring to Figures l to 6 of the drawings, the ceiling rose comprises an upper lixed part generally indicated by 11 and a lower detachable part generally indicated by 12. The lower portion of the upper part 11 is formed with an undercut groove 13 slightly tapering towards its closed end 14, while the upper portion of the lower part 12 is likewise slightly tapered and formed with bevelled edges or sides 31a, so that the said lower part 12 can slide into the groove 13 and be firmly located in position therein as described more fully hereinunder.

The upper part 11 consists of a circular casting 15 of chromium plated metal or of other material, for example metallised impact styrene, and a central insulating circular plug 16 which latter is provided with three terminals or contact members 17. The casting 15 includes an upper annular rim 18, and intermediate wall 19 (Figure 3) and a lower portion 20 in which the groove 13 is formed. The intermediate wall 19 is provided with two diametrically opposite holes 21 for receiving fixing screws for fastening the part 11 to a ceiling or equivalent. 'Ihe said wall 19 also has a central aperture 22 for receiving the plug 16. The plug 16 comprises two parts, a lower part 16a and an upper part 1Gb, The lower part 16a is provided with an annular flange 23 which is secured to the wall 19 of the casting 15 by two set screws 32, the part 16a passing through the aperture 22 in the wall 19. The upper part 16b is secured to the lower part 16a by a central fixing screw 24 which cooperates: with an internally screw-threaded insert 25 in the part 16a. The lower surface of the upper part 1617 is provided. integrally with two small spigots (not shown) which cooperate with corresponding holes (not shown) in the lower part 16a to locate the two parts in correct relative position.

The terminals or contact members 17 `are located in apertures in the plug 16, said members being provided intermediate their ends with small flanges 17a which are housed in corresponding cavities in the lower part 16a and held therein by the upper part 16b.

The upper ends of the members 1'7 are provided with axial bores 26 to receive the ends of electric lead-in wires (not shown). The wires may be secured in position by set screws 3S inclined as shown for accessibility. The lower ends of the members 17 are each formed with a concave surface 1711 for co-operation with the contact members in the lower detachable part to be described.

The lower surface of the lower part 16a of the plug 16 is formed with three grooves or channels 43. These channels are of constant depth and extend. from the edge of the plug 16 to the corresponding contact member17, the concave surfaces 17b of said members forming small cavities at the inner ends of said channels. Owing to the disposition of the members 17 the middle channel 43 is shorterthan the two side channels. rThis construction avoids or reduces risk of the contact members 17 being accidentally touchedV by anyone when the detachable part of the connector is removed from the fixed part. it also ensures that the two parts of the connector are locked together when the terminals of the lower detachable part of the connector to be described are in register with the contact members 17.

The lower detachable part 12 of the connector consists of a casting 27 of the same material as the casting 15 and a central insulating circular plug 28 which latter is provided with three spring-loaded terminals or contact members 29. The casting 27 consists of a lower tubular portion 30 and an upper portion 31 which is formed integrally with the bevelled or outwardly inclined sides 31a previously referred to. As indicated above these sides 31a are slightly further apart at one end of the detachable part than at the other end thereof and are joined at the Wider end by a curved wall portion 33 which completes the annular periphery of the upper part 11 when the two parts 11 and 12 are in position. The narrower end of the upper portion 31 of the detachable part 12 is provided with two upwardly projecting studs 3'4 of the same height as the inclined sides 31a to facilitate the insertion of the casting 27 into the undercut groove 13. The lower tubular portion 3) of the part 12 is screw-threaded internally to receive a hook 35 or equivalent from which a lamp bowl or other electrical fitting may be suspended, for example by a chain. The hook 35 may of course be replaced by a closed ring or alternatively it may be replaced by a hollow rod screw-threaded at its upper end, the electric wires passing through this rod to the electric light fittings supported thereby.

The central insulating plug 28 of the lower detach-able part 12 which is of cylindrical shape so that it can fit within the tubular portion 3() of the lower part 12 comprises two parts, an upper part 28a and a lower part 2gb. The upper part 28a is provided with an annular flange 36 which is secured to the casting 27 by two set screws 37. The upper part 28a is secured to the lower part 28h by a central fixing screw 41 which co-operates with an internally screw-threaded insert 42 in the part 28a.

The terminals or contact members 29 are located in apertures in the plug 28, said members being provided intermediate their ends with small fianges 29a which are housed in corresponding cavities in the upper part 28a and held therein by the lower part 28h. The upper ends 29b of the members 29 are spring-loaded as indicated Y above. 'Ihese ends project above the level of the upper surface of the plug 2,8y and are of convex shape for cooperation with the concave lower surfaces of the contact members 17 in the upper plug 16. The lower ends of the members 29 are transversely apertured and provided with set screws 39 for the attachment of electric wires (not shown) which pass through a bore 40 in the lower end of part 12. The cavities in the lower part 2812 of the plug 28 may have an inclined face (not shown) to facilitate the insertion of the corresponding wires in the terminal apertures. The upper surface of the lower part 28b is provided integrally with two small spigots (not shown) which co-operate with corresponding holes (not Shown) in the upper part 28a to locate the two parts in the correct relative position.

When the detachable part 12 is slid into position in the upper fixed part 11 in the direction of the arrow A in Figure l, the spring loaded terminals 29 freely enter the grooves 43, but owing to the slight taper of the parts the detachable part 12 is caused to ride up the sides of the groove 13 and tighten against the upper part 11 thus compressing the spring loaded terminals 29. When the ends ofthe grooves 43 are reached the convex upper ends 29b enter the recesses formed by the concave surfaces 1711l ofthe upper terminal members 17, and engage said surfaces under the action of the springs (not shown) in the members 29 to locate the two parts 11 and 12 of the connector firmly in position and thus prevent accidental separation thereof.

The hotles 21 in the wall 19 of the casting 15 are preferably disposed at opposite sides of the groove 13 so that they are clear of the spring loaded terminals 29 during the insertion of the lower part 12 of the connector in the upper part 11.

Instead of being made in two parts, each insulating plug 16, 23 may be moulded in one piece with the contact members permanently located therein.

The modified construction shown in Figures 7, 8 and 9 comprises an upper fixed part 111 and a lower detachable part 112 formed with bevelled edges 31a so that it is slidable into 'and out of the groove 13 in the fixed part 111 as described above with reference to Figures 1 to 6.

The upper part 111 comprises Ia circular metal casting 115 and a one-piece central insulating plug 116 which carries spring-loaded terminals or contact members 117 with convex lower ends 117a. An intermediate wall 119 of the casting 115 is provided in the undercut groove with two diarnetrically opposite holes 121 for fixing purposes. The wall 119 has a central aperture 122, 122a which receives the plug 116. This plug 116 is formed with an annular flange 123 adapted to be located in the lower part 122a of the said central aperture, the main body of the plug passing through the upper part 122 of said aperture. Two positioning studs (not shown) are also formed on the plug fiange 123 for co-operation with small apertures (not shown) in the wall 119 adjacent the central aperture therein. The plug 116 is also formed with three apertures adapted to receive three spring-loaded terminals 117 as required for a normal 3-point circuit.

In this construction the spring-loaded terminals 117 are assembled in the upper casting as follows: the plug 116 is located from underneath in the central aperture in the casting, a fibre or like annular plate 124 is placed on the all 119 around said plug, the terminals 117 are inserted from above in the corresponding apertures in the plug and a small fibre or like disc 125 of the same diameter as the upper part of the plug is fixed in position by means of screws 126 on the upper ends of the plug to hold the terminals 117 in position.

When thus assembled the lower ends 117a of the springloaded terminals project a short distance into the undercut groove, one nearer the open end of said groove and the other two equidistant therefrom and nearer the closed end 114 of the groove. The upper ends of the terminals 117 are provided with set screws 146 for the attachment of electric wire (not shown).

The lower detachable part 112 of the connector consists of a metal casting 127 as in the yconstruction of Figures 1 to 6, and -a central one-piece insulating plug 128 provided with fixed-contact members 129.Y The narrower end of the slide portion 131 is pro-vided with two upwardly projecting studs 34 as in the construction of Figures 1 to 6 to facilitate the insertion of the metal casting 127 into the undercutV groove and ensure that during insertion the said casting 127 does not touch the downwardly projecting terminals 117 in said groove. A hook 35 or equivalent is provided as before.

The plug 128 is of cylindrical shape so that it can tit into the casting 127 and has an annular flange 136 at its upper end through which a set screw 137 can be passed to locate the plug in position. The plug is provided with three fixed contact members 129 in positions corresponding with the positions of the terminals 117 in the upper part of the connector. rihe lower ends of the members 129 are provided with set screws 139 for attachment to electric wires (not shown) in known manner.

The contact members 129 each comprise two parts 141 and 142, the upper part 142 having a screw-threaded bore for co-operation with the screw-threaded upper end La 4..' TML of reduced diameter of the lower part 141, the upper end surface 138 of each part 142 being formed with a screwdriver slot therein. The said surfaces 138 are slightly concave so that when the lower part of the connector is slid into position, the convex lower ends 117a ofthe spring-loaded terminals 117 engage resiliently in the concave upper surfaces 138 of the contact members 129 under the influence of the springs (not shown) in the terminal members 117 to locate the two parts 111 and 112 in position so that they cannot be accidentally separated. The upper surface of the plug 128 is formed with an inclined or chamfered portion 144 so that when the lower part of the connector is slid into the undercut grove in the upper part, the spring-loaded ends of the terminals 117 are first pressed upwards by said inclined surface so that the terminal springs are compressed before the terminals in the two parts reach their registering positions. The slight taper of the undercut groove and the part with -bevelled edge cooperating therewith 4also serves to compress the terminal springs before the terminals are in register position.

1t will of course be understood that the invention is not limited to the particular constructions described above. For example, a connector may be used as a wall fitting or even modified for connecting two sets of wires to one another. The number of contact members in each part may lalso be varied.

The undercut groove in the fixed upper part and the bevelled upper portion of the lower part are of such relative sizes that when the vterminals are in register the lower part can be moved slightly upwardly in the upper part against the resilient action of the spring-loaded terminals so that jamming of the two parts during use is avoided.

It will be appreciated that the undercut groove is onmed in the under surface of the upper part so that this groove is actually inverted.

in the further modification shown in Figure the circular upper part 211 of the ceiling rose is provided with lugs -at its upper edge, one of which is shown at 212, so that the said part 211 can be secured by nuts and bolts 213 to an inlet box 214 mounted in known manner in the ceiling, the said bolts passing through apertures in the said lugs and in the lower circular plate 215 of the said part 214, the said plate being disposed flush with the ceiling surface 216. An annui-ar rubber grom-met 217 is provided in a central aperture in the said lower plate 215 for the pass-age of the electric wires (not shown) from the box to two terminal screws 218, 219 with fixing nuts 220, 221 carried by the insulating plug 222 of the upper part 211 of the ceiling rose. An opening (not shown) is yalso provided in the box 214 for the entry of the wires into the' box. A cover plate 223 is arranged to fit removably around the upper part 211 of the rose, by means not shown, to give an attractive finished appearance. The interlocking of the parts is effected by the terminals as in either of the preceding constructions.

ln a further modification the spring-loaded terminals in one part have flat contact surfaces and engage corresponding flat or rounded contact surfaces in the other part without locking, the locking of the two parts being independently obtained by `a spring-loaded ball or equivalent in one part engaging with a concave surface in the other part.

I claim:

1. An electrical connector for ceiling and wall fittings comprising a fixed part adapted to be mounted on a sup porting surface and having an exposed face surface and a side wall, said fixed part face surface having a groove formed therein, said groove having a recessed surface disposed parallel to said face surface, a pair of inwardly diverging side surfaces recessed behind said face surface, one end of said groove opening through said side wall and the other end of said groove terminating short of said side wall, said side surfaces converging from said groove open end to said groove closed wall, a detachable part including a plate portion adapted to close said groove in said face surface, a hollow fixture supporting portion projecting from said plate portion, a pair of support flanges projecting from said edges of said plate portion remote from said fixture supporting portion, said support flanges diverging away from said plate portion and converging from one end to another, said flanges being complementary to said side surfaces wherebyas said flanges are slid into said groove, said plate portion is drawn into the plane of said face surface, an end flange secured to said flanges at said one end for closing the open end of said groove, a rst insulated fitting in said fixed part and opening through said recessed surface into said groove, a second insulated fitting seated in said second part and opening through said plate portion between said flanges, one of said insulated fittings having a plurality of fixed contacts disposed therein, said fixed contacts having exposed recessed ends, the other of said insulated fittings having a like number and arrangement of projecting contacts with ends complemental to said fixed contact ends to form interlocks therewith, said projecting contacts being mounted for limited movement and being spring loaded whereby said projecting contacts snap into said xed contacts as said detachable part is snapped into said fixed part with the interlock between said contacts releasably holding said detachable part relative to said fixed part.

2. The electrical connector of claim l wherein said one insulated fitting is carried by said fixed part and said projecting contacts ride along said recessed surface prior to engagement with said fixed contacts.

3. The electrical connector of claim 2 wherein said fixed contacts are recessed in said one insulated fitting and said one insulated fitting has grooves in the exposed end thereof with said grooves opening through said one insulated fitting towards said groove open end, whereby -said projecting contacts are guided into :alignment with said fixed contacts as said detachable part is engaged with said fixed part.

References Cited in the file of this patent UNITED STATES PATENTS 1,222,022 Paul Apr. 10, 1917 1,595,972 De Reamer Aug. 10, 1926 2,290,816 Schauer July 21, 1942 2,731,609 Sobel Jan. 17, 1956 2,774,951 Kinkaid Dec. 18, 1956 FOREIGN PATENTS 615,692 Great Britain lan. 10, 1949 

